This document relates to speech enhancement in a breathing apparatus.
There are numerous situations which require the use of a breathing apparatus such as the absence of a breathable atmosphere or the potential for this condition. An exemplary breathing apparatus consists of a face mask with a regulator that supplies air from a high pressure hose on demand from the user. The high pressure hose is usually connected to an air tank. When the pressure in the air tank falls below a set level, a low air alarm is generated to warn the user. A common low air alarm is generated by a valve in the regulator which releases pulses of air which can easily be sensed by the user. These pulses of air can produce pressure levels inside the mask which exceed the user's voice pressure levels. These high levels of pressure can act as interfering noise that can make tasks such as communication or automatic speech recognition more difficult.
A second source of interfering noise results from the turbulence of the air or gas released into the breathing mask by the regulator during inhalation. Inhalation noise may be reduced by turning a microphone off when the pressure drops.
Inhalation noise may be detected and attenuated by measuring the frequency response of a breathing mask to determine resonances and antiresonances, and by acting on this information.